Ovens are commonly used to cook or bake food items for consumption. Proper preparation of the food during which all portions are properly heated is a frequent problem. For example, some portions may be properly heated while still other portions are underheated or, conversely, overheated and even scorched.
This problem exists with the preparation of all food items, but is particularly accentuated in the case of food items which by their nature have different portions requiring rather widely differing heating techniques. Examples of such food items are those of the type including a crust portion having a filler portion lying over the crust portion, such as pizzas, open-faced pies, tacos, (before they are turned into the familiar roll form), and the like. In such cases, the crust portion requires a relatively low heat to avoid scorching and for a relatively prolonged time to impart the appealing and appetizing brown color and crunchy texture to the crust. On the other hand, the filler portion which can comprise many diverse foods and mixtures of foods such as cheeses, meat bits, peppers, eggs, small fish, fillings based on fruit fillings, etc., are not nearly as susceptible to scorching as a flaky crust and can be heated much more quickly and at higher temperatures as compared to the crust portion.
Especially in the so-called fast-food outlets where quick preparation and serving of a food item are highly desirable, diverse heating requirements of crust and filler portion can result in improperly prepared foods. The problems in heating food items of the type described are also accentuated when such items are heated from a frozen condition.
Prior ovens have not solved the problem encountered in heating food items having food portions of diverse heating requirements. U.S. Pat. No. 3,265,861 to Perlman discloses an electric oven for heating frozen foods in which the food is heated first by conduction to melt ice crystals and then heated by infrared rays to a higher temperature.
U.S. Pat. No. 3,626,155 to Joeckel discloses an electric oven for heating frozen foods in containers placed on plates having a thermal conductivity approximately equivalent to that of the food. The oven includes means for pulsing heat energy upward through the plate and container into the food at timed intervals, and pulsing infrared heat downwardly into the food at a predetermined wave length range while reflecting a portion of the infrared heat to produce an ambient condition. The air temperature within the oven is also regulated. This is said to produce a tolerable rate of temperature rise in the food by conduction, radiation, and convection.
U.S. Pat. No. 3,655,942 to Tosmic discloses the use of electrically energized heating tubes mounted in the upper and lower portions of an oven. A rack of open-mesh construction is positioned within the oven and intermediate the upper and lower tubes to support food items to be cooked.